A charged particle beam device represented by a critical dimension scanning electron microscope (CD-SEM) for semiconductor wafer measurement is a device which forms an image based on signals (secondary electrons and/or reflected electrons) obtained by scanning a sample with a charged particle beam. As an object of inspection and measurement using the CD-SEM, there is a semiconductor device.
Miniaturization of the semiconductor device is advanced for improvement of device performance and circuit performance. Requirement for killer contaminations or particles permitted in the semiconductor device is getting also more severe by the miniaturization of the semiconductor device. As specific examples of contaminations or particles, there are contaminations due to outgas of the semiconductor device itself, minute contaminations or particles brought by the semiconductor device, dust from a sliding portion of the CD-SEM, and the like.
The contaminations or particles float in a vacuum sample chamber and attach to a stage, an objective lens, a wall of the sample chamber, and the like. If contaminations or particles attach to the semiconductor device being measured, there is a possibility that the yield is reduced, and accordingly management thereof is required. In current circumstances, contaminations or particles are measured periodically and, when they become out of specifications, a part of generation of contaminations or particles is cleaned with ethanol to remove contaminations or particles.
On the other hand, Patent Literature 1 discloses a method for removing contaminations or particles effectively while suppressing the contaminations or particles from attaching to a sample by turning off or reducing magnetization for an objective lens for focusing an electron beam or by turning off or lowering an applied voltage of a boosting plate for accelerating the electron beam while passing through the objective lens when the sample is removed from beneath the objective lens.